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Item Fate and Characteristics of Dissolved Organic Nitrogen through Wastewater Treatment Systems(North Dakota State University, 2012) Simsek, HalisDissolved organic nitrogen (DON) represents a significant portion (25-80%) of total dissolved nitrogen in the final effluent of wastewater treatment plants (WWTPs). DON in treated wastewater, once degraded, causes oxygen depletion and/or eutrophication in receiving waters and should be reduced prior to discharge. Biodegradability, bioavailability, and photodegradability are important characteristics of wastewater derived DON and are subjects of research in this dissertation. Four research tasks were performed. In the first task, laboratory-scale chemostat experiments were conducted to examine whether solids retention time (SRT) could be used to control DON and biodegradable DON (BDON) in treated wastewater. Nine different SRTs from 0.3 to 13 were studied. There was no correlation between effluent DON and SRTs. However, BDONs at SRTs of 0.3 to 4 days were comparable and had a decreasing trend with SRTs after that. These results indicate the benefit of high SRTs in term of producing effluent with less BDON. The second task was a comprehensive year-round data collection to study the fate of DON and BDON through the treatment train of a trickling filter (TF) WWTP. The plant removed substantial amounts of DON (62%) and BDON (76%) mainly through the biological process. However, the discharged concentrations in the effluent were still high enough to be critical for a stringent total nitrogen discharge limit (below 5 mg-N/L). Evolution of bioavailable DON (ABDON) along the treatment trains of activated sludge (AS) and TF WWTPs and relationship between ABDON and BDON were examined in the third task. ABDON exerted from a combination of bacteria and algae inocula was higher than algae inoculated ABDON and bacteria inoculated BDON suggesting the use of algae as a treatment organism along with bacteria to minimize effluent DON. The TF and AS WWTPs removed 88% and 64% of ABDON, respectively. In the last task, photodegradable DON (PDON) in primary wastewater and final effluent from TF and AS WWTPs was studied. PDON and BDON fractions of DON data in the final effluent of TF and AS WWTP samples elucidate that photodegradation is as critically important as biodegradation when mineralization of effluent DON is a concern in receiving waters.Item Development of Operational Strategies to Minimize Bromate Formation in the Moorhead Water Treatment Plant(North Dakota State University, 2014) Young, Kevin BradleyA recent study at the Moorhead water treatment plant (MWTP) determined that bromate formed during ozone disinfection and, at times, exceeded the maximum contaminant level (MCL) of 10 parts per billion (ppb) in the summer months. Operational data showed that bromate formation was directly related to raw water bromide concentration and control of the ozone system. This study was conducted with the purpose of developing and implementing operational strategies to minimize bromate formation in the MWTP. Several operational changes, including selection of source water based on bromide concentration and controlling ozone addition in a manner that reduces the ozone dose used to achieve disinfection, were implemented and were effective at minimizing bromate formation in the ozone chambers. The bromate concentration in the finished drinking water was significantly reduced and only a few samples contained greater than 10 ppb bromate.Item An Investigation into Bromate Formation in Ozone Disinfection Systems(North Dakota State University, 2013) Storlie, LesleeOzonation is used as an alternative disinfection process to chlorination but unfortunately has a potential of oxidizing bromide, a natural component of water sources, to bromate. Bromate is a possible carcinogen with a maximum contaminant level of 10 ppb. To understand bromate formation in full-scale systems, a comprehensive study was conducted at the Moorhead Water Treatment Plant (WTP). Bromide concentrations in source waters were monitored. Water samples from locations in the ozonation chambers were collected and analyzed for bromate and other parameters. Results showed that bromate formation was increased through increases in pH, bromide, and ozone dose during high temperatures and was decreased by increases in organics. The impact of the bromate influential parameters was minimized at low temperatures. To assist Moorhead WTP on developing bromate control strategies, a modeling approach was adopted to predict bromate formation at various operational conditions using temperature, pH, ozone dose, bromide, and TOC.